Medical Essays by Oliver Wendell Holmes, Sr. (The Physician and Poet)

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Again, see how the "bilious" theory works in every-day life here andnow, illustrated by a case from actual life. A youthfulpractitioner, whose last molars have not been a great while cut,meets an experienced and noted physician in consultation. This isthe case. A slender, lymphatic young woman is suckling two lustytwins, the intervals of suction being occupied on her part withpalpitations, headaches, giddiness, throbbing in the head, andvarious nervous symptoms, her cheeks meantime getting bloodless, andher strength running away in company with her milk. The oldexperienced physician, seeing the yellowish waxy look which is commonin anaemic patients, considers it a "bilious" case, and is for givinga rousing emetic. Of course, he has to be wheedled out of this, arecipe is written for beefsteaks and porter, the twins areignominiously expelled from the anaemic bosom, and forced to takeprematurely to the bottle, and this prolific mother is saved forfuture usefulness in the line of maternity.

The practice of making a profit on the medicine ordered has been heldup to reprobation by one at least of the orators who have precededme. That the effect of this has been ruinous in English practice Icannot doubt, and that in this country the standard of practice wasin former generations lowered through the same agency is notunlikely. I have seen an old account-book in which the physiciancharged an extra price for gilding his rich patients' pills. If allmedicine were very costly, and the expense of it always came out ofthe physician's fee, it would really be a less objectionablearrangement than this other most pernicious one. He would naturallythink twice before he gave an emetic or cathartic which evacuated hisown pocket, and be sparing of the cholagogues that emptied thebiliary ducts of his own wallet, unless he were sure they wereneeded. If there is any temptation, it should not be in favor ofgiving noxious agents, as it clearly must be in the case of Englishdruggists and "General Practitioners." The complaint against theother course is a very old one. Pliny, inspired with as truly Romanhorror of quackery as the elder Cato,--who declared that the Greekdoctors had sworn to exterminate all barbarians, including theRomans, with their drugs, but is said to have physicked his own wifeto death, notwithstanding,--Pliny says, in so many words, that thecerates and cataplasms, plasters, collyria, and antidotes, soabundant in his time, as in more recent days, were mere tricks tomake money.

A pretty strong eddy, then, or rather many eddies, setting constantlyback from the current of sober observation of nature, in thedirection of old superstitions and fancies, of exploded theories, ofold ways of making money, which are very slow to pass out of fashion

But there are other special American influences which we are bound totake cognizance of. If I wished to show a student the difficultiesof getting at truth from medical experience, I would give him thehistory of epilepsy to read. If I wished him to understand thetendencies of the American medical mind, its sanguine enterprise, itsself-confidence, its audacious handling of Nature, its impatiencewith her old-fashioned ways of taking time to get a sick man well, Iwould make him read the life and writings of Benjamin Rush. Dr. Rushthought and said that there were twenty times more intellect and ahundred times more knowledge in the country in 1799 than before theRevolution. His own mind was in a perpetual state of exaltationproduced by the stirring scenes in which he had taken a part, and thequickened life of the time in which he lived. It was not the stateto favor sound, calm observation. He was impatient, and Nature isprofoundly imperturbable. We may adjust the beating of our hearts toher pendulum if we will and can, but we may be very sure that shewill not change the pendulum's rate of going because our hearts arepalpitating. He thought he had mastered yellow-fever. "Thank God,"he said, "out of one hundred patients whom I have visited orprescribed for this day, I have lost none." Where was all his legacyof knowledge when Norfolk was decimated? Where was it when the blueflies were buzzing over the coffins of the unburied dead piled up inthe cemetery of New Orleans, at the edge of the huge trenches yawningto receive them?

One such instance will do as well as twenty. Dr. Rush must have beena charming teacher, as he was an admirable man. He was observing,rather than a sound observer; eminently observing, curious, even,about all manner of things. But he could not help feeling as ifNature had been a good deal shaken by the Declaration ofIndependence, and that American art was getting to be rather too muchfor her,--especially as illustrated in his own practice. He taughtthousands of American students, he gave a direction to the medicalmind of the country more than any other one man; perhaps he typifiesit better than any other. It has clearly tended to extravagance inremedies and trust in remedies, as in everything else. How could apeople which has a revolution once in four years, which has contrivedthe Bowie-knife and the revolver, which has chewed the juice out ofall the superlatives in the language in Fourth of July orations, andso used up its epithets in the rhetoric of abuse that it takes twogreat quarto dictionaries to supply the demand; which insists insending out yachts and horses and boys to out-sail, out-run, out-fight, and checkmate all the rest of creation; how could such apeople be content with any but "heroic" practice? What wonder thatthe stars and stripes wave over doses of ninety grains of sulphate ofquinine, [More strictly, ninety-six grains in two hours. Dunglison'sPractice, 1842, vol. ii. p. 520. Eighty grains in one dose.Ibid. p. 536. Ninety-six grains of sulphate of quinine are equalto eight ounces of good bark.--Wood & Bache.] and that the Americaneagle screams with delight to see three drachms of calomel given at asingle mouthful?

Add to this the great number of Medical Journals, all useful, wehope, most of them necessary, we trust, many of them excellently wellconducted, but which must find something to fill their columns, andso print all the new plans of treatment and new remedies they can gethold of, as the newspapers, from a similar necessity, print theshocking catastrophes and terrible murders.

Besides all this, here are we, the great body of teachers in thenumberless medical schools of the Union, some of us lecturing tocrowds who clap and stamp in the cities, some of us wandering overthe country, like other professional fertilizers, to fecundate theminds of less demonstrative audiences at various scientific stations;all of us talking habitually to those supposed to know less thanourselves, and loving to claim as much for our art as we can, not tosay for our own schools, and possibly indirectly for our ownpractical skill. Hence that annual crop of introductory lectures;the useful blossoming into the ornamental, as the cabbage becomesglorified in the cauliflower; that lecture-room literature ofadjectives, that declamatory exaggeration, that splendid show oferudition borrowed from D'Israeli, and credited to Lord Bacon and therest, which have suggested to our friends of the Medical Journals anoccasional epigram at our expense. Hence the tendency in theseproductions, and in medical lectures generally, to overstate theefficacy of favorite methods of cure, and hence the premium offeredfor showy talkers rather than sagacious observers, for the men ofadjectives rather than of nouns substantive in the more ambitious ofthese institutions.

Such are some of the eddies in which we are liable to become involvedand carried back out of the broad stream of philosophical, or, inother words, truth-loving, investigations. The causes of disease, inthe mean time, have been less earnestly studied in the eagerness ofthe search for remedies. Speak softly! Women have been borne outfrom an old-world hospital, two in one coffin, that the horrors oftheir prison-house might not be known, while the very men who werediscussing the treatment of the disease were stupidly conveying theinfection from bed to bed, as rat-killers carry their poisons fromone household to another. Do not some of you remember that I havehad to fight this private-pestilence question against a scepticismwhich sneered in the face of a mass of evidence such as the calmstatisticians of the Insurance office could not listen to withouthorror and indignation? ["The Contagiousness of Puerperal Fever."--N. E. Quar. Jour. of Medicine and Surgery, April, 1843. Reprinted,with Additions. Boston: Ticknor & Fields. 1855.] Have we forgottenwhat is told in one of the books published under our own sanction,that a simple measure of ventilation, proposed by Dr. John Clark, hadsaved more than sixteen thousand children's lives in a singlehospital? How long would it have taken small doses of calomel andrhubarb to save as many children? These may be useful in prudenthands, but how insignificant compared to the great hygienicconditions! Causes, causes, and again causes,--more and more we fallback on these as the chief objects of our attention. The shortestsystem of medical practice that I know of is the oldest, but not theworst. It is older than Hippocrates, older than Chiron the Centaur.Nature taught it to the first mother when she saw her first-bornchild putting some ugly pebble or lurid berry into its mouth. I knownot in what language it was spoken, but I know that in English itwould sound thus: Spit it out!

Art can do something more than say this. It can sometimes reach thepebble or berry after it has been swallowed. But the great thing isto keep these things out of children's mouths, and as soon as theyare beyond our reach, to be reasonable and patient with Nature, whomeans well, but does not like to hurry, and who took nine calendarmonths, more or less, to every mother's son among us, before shethought he was fit to be shown to the public.

Suffer me now to lay down a few propositions, whether old or new itmatters little, not for your immediate acceptance, nor yet for yourhasty rejection, but for your calm consideration.

But first, there are a number of terms which we are in the habit ofusing in a vague though not unintelligible way, and which it is aswell now to define. These terms are the tools with which we are towork, and the first thing is to sharpen them. It is nothing to usthat they have been sharpened a thousand times before; they alwaysget dull in the using, and every new workman has a right to carrythem to the grindstone and sharpen them to suit himself.

Nature, in medical language, as opposed to Art, means trust in thereactions of the living system against, ordinary normal impressions.

Art, in the same language, as opposed to Nature, means an intentionalresort to extraordinary abnormal impressions for the relief ofdisease.

The reaction of the living system is the essence of both. Food isnothing, if there is no digestive act to respond to it. We cannotraise a blister on a dead man, or hope that a carminative forcedbetween his lips will produce its ordinary happy effect.

Disease, dis-ease,--disturbed quiet, uncomfortableness,--meansimperfect or abnormal reaction of the living system, and its more orless permanent results.

Food, in its largest sense, is whatever helps to build up the normalstructures, or to maintain their natural actions.

Medicine, in distinction from food, is every unnatural or noxiousagent applied for the relief of disease.

Physic means properly the Natural art, and Physician is only theGreek synonyme of Naturalist.

With these few explanations I proceed to unfold the propositions Ihave mentioned.

Disease and death, if we may judge by the records of creation, areinherently and essentially necessary in the present order of things.A perfect intelligence, trained by a perfect education, could do nomore than keep the laws of the physical and spiritual universe. Animperfect intelligence, imperfectly taught,--and this is thecondition of our finite humanity,--will certainly fail to keep allthese laws perfectly. Disease is one of the penalties of one of theforms of such failure. It is prefigured in the perturbations of theplanets, in the disintegration of the elemental masses; it has leftits traces in the fossil organisms of extinct creations. [ProfessorAgassiz has kindly handed me the following note: "There are abnormalstructures in animals of all ages anterior to the creation ofmankind. Malformed specimens of Crinoids are known from the Triassicand Jurassic deposits. Malformed and diseased bones of tertiarymammalia have been collected in the caverns of Gailenreuth withtraces of healing."]

But it is especially the prerogative, I had almost said privilege, ofeducated and domesticated beings, from man down to the potato,serving to teach them, and such as train them, the laws of life, andto get rid of those who will not mind or cannot be kept subject tothese laws.

Disease, being always an effect, is always in exact proportion to thesum of its causes, as much in the case of Spigelius, who dies of ascratch, as in that of the man who recovers after an iron bar hasbeen shot through his brain. The one prevalent failing of themedical art is to neglect the causes and quarrel with the effect.

There are certain general facts which include a good deal of what iscalled and treated as disease. Thus, there are two oppositemovements of life to be seen in cities and elsewhere, belonging toraces which, from various persistent causes, are breeding down andtending to run out, and to races which are breeding up, oraccumulating vital capital,--a descending and an ascending series.Let me give an example of each; and that I may incidentally remove acommon impression about this country as compared with the Old World,an impression which got tipsy with conceit and staggered into theattitude of a formal proposition in the work of Dr. Robert Knox, Iwill illustrate the downward movement from English experience, andthe upward movement from a family history belonging to this immediateneighborhood.

Miss Nightingale speaks of "the fact so often seen of agreat-grandmother, who was a tower of physical vigor, descending intoa grandmother perhaps a little less vigorous, but still sound as abell, and healthy to the core, into a mother languid and confined toher carriage and house; and lastly into a daughter sickly andconfined to her bed." So much for the descending English series; nowfor the ascending American series.

Something more than one hundred and thirty years ago there graduatedat Harvard College a delicate youth, who lived an invalid life anddied at the age of about fifty. His two children were both ofmoderate physical power, and one of them diminutive in stature. Thenext generation rose in physical development, and reached eightyyears of age and more in some of its members. The fourth generationwas of fair average endowment. The fifth generation, great-great-grandchildren of the slender invalid, are several of, them ofextraordinary bodily and mental power; large in stature, formidablealike with their brains and their arms, organized on a more extensivescale than either of their parents.

This brief account illustrates incidentally the fallacy of theuniversal-degeneration theory applied to American life; the same onwhich one of our countrymen has lately brought some very forciblefacts to bear in a muscular discussion of which we have heard rathermore than is good for us. But the two series, American and English,ascending and descending, were adduced with the main purpose ofshowing the immense difference of vital endowments in differentstrains of blood; a difference to which all ordinary medication is inall probability a matter of comparatively trivial purport. Manyaffections which art has to strive against might be easily shown tobe vital to the well-being of society. Hydrocephalus, tabesmesenterica, and other similar maladies, are natural agencies whichcut off the children of races that are sinking below the decentminimum which nature has established as the condition of viability,before they reach the age of reproduction. They are really not somuch diseases, as manifestations of congenital incapacity for life;the race would be ruined if art could ever learn always to preservethe individuals subject to them. We must do the best we can forthem, but we ought also to know what these "diseases" mean.

Again, invalidism is the normal state of many organizations. It canbe changed to disease, but never to absolute health by medicinalappliances. There are many ladies, ancient and recent, who areperpetually taking remedies for irremediable pains and aches. Theyought to have headaches and back-aches and stomach-aches; they arenot well if they do not have them. To expect them to live withoutfrequent twinges is like expecting a doctor's old chaise to gowithout creaking; if it did, we might be sure the springs werebroken. There is no doubt that the constant demand for medicinalremedies from patients of this class leads to their over-use; oftenin the case of cathartics, sometimes in that of opiates. I have beentold by an intelligent practitioner in a Western town, that theconstant prescription of opiates by certain physicians in hisvicinity has rendered the habitual use of that drug in all thatregion very prevalent; more common, I should think, than alcoholicdrunkenness in the most intemperate localities of which I have knownanything. A frightful endemic demoralization betrays itself in thefrequency with which the haggard features and drooping shoulders ofthe opium-drunkards are met with in the streets.

The next proposition I would ask you to consider is this:The presumption always is that every noxious agent, includingmedicines proper, which hurts a well man, hurts a sick one.[ Note B.]

Let me illustrate this proposition before you decide upon it. If itwere known that a prize-fighter were to have a drastic purgativeadministered two or three days before a contest, or a large blisterapplied to his back, no one will question that it would affect thebetting on his side unfavorably; we will say to the amount of fiveper cent. Now the drain upon the resources of the system produced insuch a case must be at its minimum, for the subject is a powerfulman, in the prime of life, and in admirable condition. If the drugor the blister takes five per cent. from his force of resistance, itwill take at least as large a fraction from any invalid. But thisinvalid has to fight a champion who strikes hard but cannot be hit inreturn, who will press him sharply for breath, but will never panthimself while the wind can whistle through his fleshless ribs. Thesuffering combatant is liable to want all his stamina, and five percent. may lose him the battle.

All noxious agents, all appliances which are not natural food orstimuli, all medicines proper, cost a patient, on the average, fiveper cent. of his vital force, let us say. Twenty times as much wasteof force produced by any of them, that is, would exactly kill him,nothing less than kill him, and nothing more. If this, or somethinglike this, is true, then all these medications are, prima facie,injurious.

In the game of Life-or-Death, Rouge et Noir, as played between theDoctor and the Sexton, this five per cent., this certain small injuryentering into the chances is clearly the sexton's perquisite forkeeping the green table, over which the game is played, and where hehoards up his gains. Suppose a blister to diminish a man's pain,effusion or dyspnoea to the saving of twenty per cent. in vitalforce; his profit from it is fifteen, in that case, for it alwayshurts him five to begin with, according to our previous assumption.

Presumptions are of vast importance in medicine, as in law. A man ispresumed innocent until he is proved guilty. A medicine--that is, anoxious agent, like a blister, a seton, an emetic, or a cathartic--should always be presumed to be hurtful. It always is directlyhurtful; it may sometimes be indirectly beneficial. If thispresumption were established, and disease always assumed to be theinnocent victim of circumstances, and not punishable by medicines,that is, noxious agents, or poisons, until the contrary was shown, weshould not so frequently hear the remark commonly, perhapserroneously, attributed to Sir Astley Cooper, but often repeated bysensible persons, that, on the whole, more harm than good is done bymedication. Throw out opium, which the Creator himself seems toprescribe, for we often see the scarlet poppy growing in thecornfields, as if it were foreseen that wherever there is hunger tobe fed there must also be pain to be soothed; throw out a fewspecifics which our art did not discover, and is hardly needed toapply [ Note C.]; throw out wine, which is a food, and the vaporswhich produce the miracle of anaesthesia, and I firmly believe thatif the whole materia medica, as now used, could be sunk to the bottomof the sea, it would be all the better for mankind,--and all theworse for the fishes.

But to justify this proposition, I must add that the injuriesinflicted by over-medication are to a great extent masked by disease.Dr. Hooker believes that the typhus syncopatia of a precedinggeneration in New England "was often in fact a brandy and opiumdisease." How is a physician to distinguish the irritation producedby his blister from that caused by the inflammation it was meant tocure? How can he tell the exhaustion produced by his evacuants fromthe collapse belonging to the disease they were meant to remove?

Lastly, medication without insuring favorable hygienic conditions islike amputation without ligatures. I had a chance to learn this wellof old, when physician to the Broad Street district of the BostonDispensary. There, there was no help for the utter want of wholesomeconditions, and if anybody got well under my care, it must have beenin virtue of the rough-and-tumble constitution which emerges from thestruggle for life in the street gutters, rather than by the aid of myprescriptions.

But if the materia medica were lost overboard, how much more painswould be taken in ordering all the circumstances surrounding thepatient (as can be done everywhere out of the crowded pauperdistricts), than are taken now by too many who think they do theirduty and earn their money when they write a recipe for a patient leftin an atmosphere of domestic malaria, or to the most negligent kindof nursing! I confess that I should think my chance of recovery fromillness less with Hippocrates for my physician and Mrs. Gamp for mynurse, than if I were in the hands of Hahnemann himself, withFlorence Nightingale or good Rebecca Taylor to care for me.

If I am right in maintaining that the presumption is always againstthe use of noxious agents in disease, and if any whom I mightinfluence should adopt this as a principle of practice, they willoften find themselves embarrassed by the imperative demand ofpatients and their friends for such agents where a case is not madeout against this standing presumption. I must be permitted to say,that I think the French, a not wholly uncivilized people, are inadvance of the English and ourselves in the art of prescribing forthe sick without hurting them. And I do confess that I think theirvaried ptisans and syrups are as much preferable to the mineralregimen of bug-poison and ratsbane, so long in favor on the otherside of the Channel, as their art of preparing food for the table tothe rude cookery of those hard-feeding and much-dosing islanders.We want a reorganized cuisine of invalidism perhaps as much as theculinary, reform, for which our lyceum lecturers, and others who livemuch at hotels and taverns, are so urgent. Will you think I amdisrespectful if I ask whether, even in Massachusetts, a dose ofcalomel is not sometimes given by a physician on the same principleas that upon which a landlord occasionally prescribes bacon andeggs,--because he cannot think of anything else quite so handy? Ileave my suggestion of borrowing a hint from French practice to yourmature consideration.

I may, however, call your attention, briefly, to the singular fact,that English and American practitioners are apt to accuse Frenchmedical practice of inertness, and French surgical practice ofunnecessary activity. Thus, Dr. Bostock considers French medicaltreatment, with certain exceptions, as "decidedly less effective"than that of his own country. Mr. S. Cooper, again, defends thesimple British practice of procuring union by the first intentionagainst the attacks of M. Roux and Baron Larrey. [Cooper's Surg.Diet. art. "Wounds." Yet Mr. John Bell gives the French surgeonscredit for introducing this doctrine of adhesion, and accusesO'Halloran of "rudeness and ignorance," and "bold, uncivil language,"in disputing their teaching. Princ. of Surgery, vol. i. p. 42.Mr. Hunter succeeded at last in naturalizing the doctrine andpractice, but even he had to struggle against the perpetual jealousyof rivals, and died at length assassinated by an insult.] We haveoften heard similar opinions maintained by our own countrymen. WhileAnglo-American criticism blows hot or cold on the two departments ofFrench practice, it is not, I hope, indecent to question whether allthe wisdom is necessarily with us in both cases.

Our art has had two or three lessons which have a deep meaning tothose who are willing to read them honestly. The use of water-dressings in surgery completed the series of reforms by which wasabolished the "coarse and cruel practice" of the older surgeons, whowith their dressings and acrid balsams, their tents and leaden tubes,"absolutely delayed the cure." The doctrine of Broussais, transientas was its empire, reversed the practice of half of Christendom for aseason, and taught its hasty disciples to shun their old favoriteremedies as mortal poisons. This was not enough permanently to shiftthe presumption about drugs where it belonged, and so at last, justas the sympathetic powder and the Unguentum Armarium came in asuperstitious age to kill out the abuses of external over-medication,the solemn farce of Homoeopathy was enacted in the face of our owntoo credulous civilization, that under shelter of its pretences the"inward bruises" of over-drugged viscera might be allowed to heal bythe first intention. Its lesson we must accept, whether we will ornot; its follies we are tired of talking about. The security of themedical profession against this and all similar fancies is in theaverage constitution of the human. mind with regard to the laws ofevidence.

My friends and brothers in Art! There is nothing to be feared fromthe utterance of any seeming heresy to which you may have listened.I cannot compromise your collective wisdom. If I have strained thetruth one hair's breadth for the sake of an epigram or an antithesis,you are accustomed to count the normal pulse-beats of sound judgment,and know full well how to recognize the fever-throbs of conceit andthe nervous palpitations of rhetoric.

The freedom with which each of us speaks his thought in thispresence, belongs in part to the assured position of the Professionin our Commonwealth, to the attitude of Science, which is alwaysfearless, and to the genius of the soil on which we stand, from whichNature withheld the fatal gift of malaria only to fill it withexhalations that breed the fever of inquiry in our blood and in ourbrain. But mainly we owe the large license of speech we enjoy tothose influences and privileges common to us all as self-governingAmericans.

This Republic is the chosen home of minorities, of the less power inthe presence of the greater. It is a common error to speak of ourdistinction as consisting in the rule of the majority. Majorities,the greater material powers, have always ruled before. The historyof most countries has been that of majorities, mounted majorities,clad in iron, armed with death treading down the tenfold morenumerous minorities. In the old civilizations they root themselveslike oaks in the soil; men must live in their shadow or cut themdown. With us the majority is only the flower of the passing noon,and the minority is the bud which may open in the next morning's sun.We must be tolerant, for the thought which stammers on a singletongue today may organize itself in the growing consciousness of thetime, and come back to us like the voice of the multitudinous wavesof the ocean on the morrow.

Twenty-five years have passed since one of your honored Presidentsspoke to this Society of certain limitations to the power of our Art,now very generally conceded. Some were troubled, some were almostangry, thinking the Profession might suffer from such concessions.It has certainly not suffered here; if, as some affirm, it has lostrespect anywhere, it was probably for other, and no doubt sufficientreasons.

Since that time the civilization of this planet has changed hands.Strike out of existence at this moment every person who was breathingon that day, May 27, 1835, and every institution of society, everyart and every science would remain intact and complete in the livingthat would be left. Every idea the world then held has been sincedissolved and recrystallized.

We are repeating the same process. Not to make silver shrines forour old divinities, even though by this craft we should have ourwealth, was this Society organized and carried on by the good men andtrue who went before us. Not for this, but to melt the gold out ofthe past, though its dross should fly in dust to all the winds ofheaven, to save all our old treasures of knowledge and mine deeplyfor new, to cultivate that mutual respect of which outward courtesyis the sign, to work together, to feel together, to take counseltogether, and to stand together for the truth, now, always, here,everywhere; for this our fathers instituted, and we accept, theoffices and duties of this time-honored Society.

BORDER LINES OF KNOWLEDGE IN SOME PROVINCES OF MEDICAL SCIENCE.

An Introductory Lecture delivered before the Medical Classof Harvard University, November 6, 1861.

[This Lecture appears as it would have been delivered had the timeallowed been less strictly, limited. Passages necessarily omittedhave been restored, and points briefly touched have been more fullyconsidered. A few notes have been added for the benefit of thatlimited class of students who care to track an author through thehighways and by-ways of his reading. I owe my thanks to several ofmy professional brethren who have communicated with me on subjectswith which they are familiar; especially to Dr. John Dean, for theopportunity of profiting by his unpublished labors, and to Dr. HasketDerby, for information and references to recent authorities relatingto the anatomy and physiology of the eye.]

The entrance upon a new course of Lectures is always a period ofinterest to instructors and pupils. As the birth of a child to aparent, so is the advent of a new class to a teacher. As the lightof the untried world to the infant, so is the dawning of the lightresting over the unexplored realms of science to the student. In thename of the Faculty I welcome you, Gentlemen of the Medical Class,new-born babes of science, or lustier nurslings, to this morning ofyour medical life, and to the arms and the bosom of this ancientUniversity. Fourteen years ago I stood in this place for the firsttime to address those who occupied these benches. As I recall thesepast seasons of our joint labors, I feel that they have been on thewhole prosperous, and not undeserving of their prosperity.

For it has been my privilege to be associated with a body of true andfaithful workers; I cannot praise them freely to their faces, or Ishould be proud to discourse of the harmonious diligence and thenoble spirit in which they have toiled together, not merely to teachtheir several branches, but to elevate the whole standard ofteaching.

I may speak with less restraint of those gentlemen who have aided mein the most laborious part of my daily duties, the Demonstrators, towhom the successive classes have owed so much of their instruction.They rise before me, the dead and the living, in the midst of themost grateful recollections. The fair, manly face and stately figureof my friend, Dr. Samuel Parkman, himself fit for the highest officesof teaching, yet willing to be my faithful assistant in the time ofneed, come back to me with the long sigh of regret for his early lossto our earthly companionship. Every year I speak the eulogy of Dr.Ainsworth's patient toil as I show his elaborate preparations: When Itake down my "American Cyclopaedia" and borrow instruction from thelearned articles of Dr. Kneeland, I cease to regret that hisindefatigable and intelligent industry was turned into a broaderchannel. And what can I say too cordial of my long associatedcompanion and friend, Dr. Hodges, whose admirable skill, workingthrough the swiftest and surest fingers that ever held a scalpelamong us, has delighted class after class, and filled our Museum withmonuments which will convey his name to unborn generations?

This day belongs, however, not to myself and my recollections, but toall of us who teach and all of you who listen, whether experts in ourspecialties or aliens to their mysteries, or timid neophytes justentering the portals of the hall of science. Look in with me, then,while I attempt to throw some rays into its interior, which shallilluminate a few of its pillars and cornices, and show at the sametime how many niches and alcoves remain in darkness.

SCIENCE is the topography of ignorance. From a few elevated pointswe triangulate vast spaces, inclosing infinite unknown details. Wecast the lead, and draw up a little sand from abysses we may neverreach with our dredges.

The best part of our knowledge is that which teaches us whereknowledge leaves off and ignorance begins. Nothing more clearlyseparates a vulgar from a superior mind, than the confusion in thefirst between the little that it truly knows, on the one hand, andwhat it half knows and what it thinks it knows on the other.

That which is true of every subject is especially true of the branchof knowledge which deals with living beings. Their existence is aperpetual death and reanimation. Their identity is only an idea, forwe put off our bodies many times during our lives, and dress in newsuits of bones and muscles.

"Thou art not thyself; For thou exist'st on many a thousand grains That issue out of dust."

If it is true that we understand ourselves but imperfectly in health,this truth is more signally manifested in disease, where naturalactions imperfectly understood, disturbed in an obscure way by half-seen causes, are creeping and winding along in the dark toward theirdestined issue, sometimes using our remedies as safe stepping-stones,occasionally, it may be, stumbling over them as obstacles.

I propose in this lecture to show you some points of contact betweenour ignorance and our knowledge in several of the branches upon thestudy of which you are entering. I may teach you a very littledirectly, but I hope much more from the trains of thought I shallsuggest. Do not expect too much ground to be covered in this rapidsurvey. Our task is only that of sending out a few pickets under thestarry flag of science to the edge of that dark domain where theensigns of the obstinate rebel, Ignorance, are flying undisputed. Weare not making a reconnoissance in force, still less advancing withthe main column. But here are a few roads along which we have tomarch together, and we wish to see clearly how far our lines extend,and where the enemy's outposts begin.

Before touching the branches of knowledge that deal with organizationand vital functions, let us glance at that science which meets you atthe threshold of your study, and prepares you in some measure to dealwith the more complex problems of the living laboratory.

CHEMISTRY. includes the art of separating and combining the elementsof matter, and the study of the changes produced by these operations.We can hardly say too much of what it has contributed to ourknowledge of the universe and our power of dealing with itsmaterials. It has given us a catalogue raisonne of the substancesfound upon our planet, and shown how everything living and dead isput together from them. It is accomplishing wonders before us everyday, such as Arabian story-tellers used to string together in theirfables. It spreads the, sensitive film on the artificial retinawhich looks upon us through the optician's lens for a few seconds,and fixes an image that will outlive its original. It questions thelight of the sun, and detects the vaporized metals floating aroundthe great luminary,--iron, sodium, lithium, and the rest,--as if thechemist of our remote planet could fill his bell-glasses from itsfiery atmosphere. It lends the power which flashes our messages inthrills that leave the lazy chariot of day behind them. It seals upa few dark grains in iron vases, and lo! at the touch of a singlespark, rises in smoke and flame a mighty Afrit with a voice likethunder and an arm that shatters like an earthquake. The dreams ofOriental fancy have become the sober facts of our every-day life, andthe chemist is the magician to whom we owe them.

To return to the colder scientific aspect of chemistry. It has shownus how bodies stand affected to each other through an almostboundless range of combinations. It has given us a most ingenioustheory to account for certain fixed relations in these combinations.It has successfully eliminated a great number of proximate compounds,more or less stable, from organic structures. It has invented otherswhich form the basis of long series of well-known compositesubstances. In fact, we are perhaps becoming overburdened with ourlist of proximate principles, demonstrated and hypothetical.

How much nearer have we come to the secret of force than Lully andGeber and the whole crew of juggling alchemists? We have learned agreat deal about the how, what have we learned about the why?

Why does iron rust, while gold remains untarnished, and goldamalgamate, while iron refuses the alliance of mercury?

The alchemists called gold Sol, the sun, and iron Mars, and pleasedthemselves with fancied relations between these substances and theheavenly bodies, by which they pretended to explain the facts theyobserved. Some of their superstitions have lingered in practicalmedicine to the present day, but chemistry has grown wise enough toconfess the fact of absolute ignorance.

What is it that makes common salt crystallize in the form of cubes,and saltpetre in the shape of six-sided prisms? We see no reason whyit should not have been just the other way, salt in prisms andsaltpetre in cubes, or why either should take an exact geometricaloutline, any more than coagulating albumen.

But although we had given up attempting to explain the essentialnature of affinities and of crystalline types, we might have supposedthat we had at least fixed the identity of the substances with whichwe deal, and determined the laws of their combination. All at oncewe find that a simple substance changes face, puts off itscharacteristic qualities and resumes them at will;--not merely whenwe liquefy or vaporize a solid, or reverse the process; but that asolid is literally transformed into another solid under our own eyes.We thought we knew phosphorus. We warm a portion of it sealed in anempty tube, for about a week. It has become a brown infusiblesubstance, which does not shine in the dark nor oxidate in the air.We heat it to 500 F., and it becomes common phosphorus again. Wetransmute sulphur in the same singular way. Nature, you know, givesus carbon in the shape of coal and in that of the diamond. It iseasy to call these changes by the name allotropism, but not the lessdo they confound our hasty generalizations.

These facts of allotropism have some corollaries connected with themrather startling to us of the nineteenth century. There may be othertransmutations possible besides those of phosphorus and sulphur.When Dr. Prout, in 1840, talked about azote and carbon being "formed"in the living system, it was looked upon as one of those freaks offancy to which philosophers, like other men, are subject. But whenProfessor Faraday, in 1851, says, at a meeting of the BritishAssociation, that "his hopes are in the direction of proving thatbodies called simple were really compounds, and may be formedartificially as soon as we are masters of the laws influencing theircombinations,"--when he comes forward and says that he has triedexperiments at transmutation, and means, if his life is spared, totry them again,--how can we be surprised at the popular story of1861, that Louis Napoleon has established a gold-factory and isglutting the mints of Europe with bullion of his own making?

And so with reference to the law of combinations. The old maxim was,Corpora non agunt nisi soluta. If two substances, a and b, areinclosed in a glass vessel, c, we do not expect the glass to changethem, unless a or b or the compound a b has the power of dissolvingthe glass. But if for a I take oxygen, for b hydrogen, and for c apiece of spongy platinum, I find the first two combine with thecommon signs of combustion and form water, the third in the mean timeundergoing no perceptible change. It has played the part of theunwedded priest, who marries a pair without taking a fee or havingany further relation with the parties. We call this catalysis,catalytic action, the action of presence, or by what learned name wechoose. Give what name to it we will, it is a manifestation of powerwhich crosses our established laws of combination at a very openangle of intersection. I think we may find an analogy for it inelectrical induction, the disturbance of the equilibrium of theelectricity of a body by the approach of a charged body to it,without interchange of electrical conditions between the two bodies.But an analogy is not an explanation, and why a few drops of yeastshould change a saccharine mixture to carbonic acid and alcohol,--alittle leaven leavening the whole lump,--not by combining with it,but by setting a movement at work, we not only cannot explain, butthe fact is such an exception to the recognized laws of combinationthat Liebig is unwilling to admit the new force at all to whichBerzelius had given the name so generally accepted.

The phenomena of isomerism, or identity of composition andproportions of constituents with difference of qualities, and ofisomorphism, or identity of form in crystals which have one elementsubstituted for another, were equally surprises to science; andalthough the mechanism by which they are brought about can be to acertain extent explained by a reference to the hypothetical atoms ofwhich the elements are constituted, yet this is only turning thedifficulty into a fraction with an infinitesimal denominator and aninfinite numerator.

So far we have studied the working of force and its seeming anomaliesin purely chemical phenomena. But we soon find that chemical forceis developed by various other physical agencies,--by heat, by light,by electricity, by magnetism, by mechanical agencies; and, viceversa, that chemical action develops heat, light, electricity,magnetism, mechanical force, as we see in our matches, galvanicbatteries, and explosive compounds. Proceeding with our experiments,we find that every kind of force is capable of producing all otherkinds, or, in Mr. Faraday's language, that "the various forms underwhich the forces of matter are made manifest have a common origin,or, in other words, are so directly related and mutually dependentthat they are convertible one into another."

Out of this doctrine naturally springs that of the conservation offorce, so ably illustrated by Mr. Grove, Dr. Carpenter, and Mr.Faraday. This idea is no novelty, though it seems so at first sight.It was maintained and disputed among the giants of philosophy.Des Cartes and Leibnitz denied that any new motion originated innature, or that any ever ceased to exist; all motion being in acircle, passing from one body to another, one losing what the othergained. Newton, on the other hand, believed that new motions weregenerated and existing ones destroyed. On the first supposition,there is a fixed amount of force always circulating in the universe.On the second, the total amount may be increasing or diminishing.You will find in the "Annual of Scientific Discovery" for 1858 a veryinteresting lecture by Professor Helmholtz of Bonn, in which it ismaintained that a certain portion of force is lost in every naturalprocess, being converted into unchangeable heat, so that the universewill come to a stand-still at last, all force passing into heat, andall heat into a state of equilibrium.

The doctrines of the convertibility or specific equivalence of thevarious forms of force, and of its conservation, which is its logicalconsequence, are very generally accepted, as I believe, at thepresent time, among physicists. We are naturally led to thequestion, What is the nature of force? The three illustriousphilosophers just referred to agree in attributing the generalmovements of the universe to the immediate Divine action. Thedoctrine of "preestablished harmony" was an especial contrivance ofLeibnitz to remove the Creator from unworthy association with theless divine acts of living beings. Obsolete as this expressionsounds to our ears, the phrase laws of the universe, which we use soconstantly with a wider application, appears to me essentiallyidentical with it.

Force does not admit of explanation, nor of proper definition, anymore than the hypothetical substratum of matter. If we assume theInfinite as omnipresent, omniscient, omnipotent, we cannot supposeHim excluded from any part of His creation, except from rebellioussouls which voluntarily exclude Him by the exercise of their fatalprerogative of free-will. Force, then, is the act of immanentDivinity. I find no meaning in mechanical explanations. Newton'shypothesis of an ether filling the heavenly spaces does not, Iconfess, help my conceptions. I will, and the muscles of my vocalorgans shape my speech. God wills, and the universe articulates Hispower, wisdom, and goodness. That is all I know. There is no bridgemy mind can throw from the "immaterial" cause to the "material"effect.

The problem of force meets us everywhere, and I prefer to encounterit in the world of physical phenomena before reaching that of livingactions. It is only the name for the incomprehensible cause ofcertain changes known to our consciousness, and assumed to be outsideof it. For me it is the Deity Himself in action.

I can therefore see a large significance in the somewhat boldlanguage of Burdach: "There is for me but one miracle, that ofinfinite existence, and but one mystery, the manner in which thefinite proceeds from the infinite. So soon as we recognize thisincomprehensible act as the general and primordial miracle, of whichour reason perceives the necessity, but the manner of which ourintelligence cannot grasp, so soon as we contemplate the nature knownto us by experience in this light, there is for us no otherimpenetrable miracle or mystery."

Let us turn to a branch of knowledge which deals with certainties upto the limit of the senses, and is involved in no speculations beyondthem. In certain points of view, HUMAN ANATOMY may be considered analmost exhausted science. From time to time some small organ whichhad escaped earlier observers has been pointed out,--such parts asthe tensor tarsi, the otic ganglion, or the Pacinian bodies; but someof our best anatomical works are those which have been classic formany generations. The plates of the bones in Vesalius, threecenturies old, are still masterpieces of accuracy, as of art. Themagnificent work of Albinus on the muscles, published in 1747, isstill supreme in its department, as the constant references of themost thorough recent treatise on the subject, that of Theile,sufficiently show. More has been done in unravelling the mysteriesof the fasciae, but there has been a tendency to overdo this kind ofmaterial analysis. Alexander Thomson split them up into cobwebs, asyou may see in the plates to Velpeau's Surgical Anatomy. I wellremember how he used to shake his head over the coarse work of Scarpaand Astley Cooper,--as if Denner, who painted the separate hairs ofthe beard and pores of the skin in his portraits, had spoken lightlyof the pictures of Rubens and Vandyk.

Not only has little been added to the catalogue of parts, but somethings long known had become half-forgotten. Louis and othersconfounded the solitary glands of the lower part of the smallintestine with those which "the great Brunner," as Haller calls him,described in 1687 as being found in the duodenum. The display of thefibrous structure of the brain seemed a novelty as shown bySpurzheim. One is startled to find the method anticipated by RaymondVieussens nearly two centuries ago. I can hardly think Gordon hadever looked at his figures, though he names their author, when hewrote the captious and sneering article which attracted so muchattention in the pages of the "Edinburgh Review."

This is the place, if anywhere, to mention any observations I couldpretend to have made in the course of my teaching the structure ofthe human body. I can make no better show than most of mypredecessors in this well-reaped field. The nucleated cells foundconnected with the cancellated structure of the bones, which I firstpointed out and had figured in 1847, and have shown yearly from thattime to the present, and the fossa masseterica, a shallow concavityon the ramus of the lower jaw, for the lodgment of the massetermuscle, which acquires significance when examined by the side of thedeep cavity on the corresponding part in some carnivora to which itanswers, may perhaps be claimed as deserving attention. I have alsopleased myself by making a special group of the six radiating muscleswhich diverge from the spine of the axis, or second cervicalvertebra, and by giving to it the name stella musculosa nuchaee. Butthis scanty catalogue is only an evidence that one may teach long andsee little that has not been noted by those who have gone before him.Of course I do not think it necessary to include rare, but alreadydescribed anomalies, such as the episternal bones, the rectussternalis, and other interesting exceptional formations I haveencountered, which have shown a curious tendency to presentthemselves several times in the same season, perhaps because thefirst specimen found calls our attention to any we may subsequentlymeet with.

The anatomy of the scalpel and the amphitheatre was, then, becomingan exhausted branch of investigation. But during the present centurythe study of the human body has changed its old aspect, and becomefertile in new observations. This rejuvenescence was effected bymeans of two principal agencies,--new methods and a new instrument.

Descriptive anatomy, as known from an early date, is to the body whatgeography is to the planet. Now geography was pretty well known solong ago as when Arrowsmith, who was born in 1750, published hisadmirable maps. But in that same year was born Werner, who taught anew way of studying the earth, since become familiar to us all underthe name of Geology.

What geology has done for our knowledge of the earth, has been donefor our knowledge of the body by that method of study to which isgiven the name of General Anatomy. It studies, not the organs assuch, but the elements out of which the organs are constructed. Itis the geology of the body, as that is the general anatomy of theearth. The extraordinary genius of Bichat, to whom more than anyother we owe this new method of study, does not require Mr. Buckle'stestimony to impress the practitioner with the importance of itsachievements. I have heard a very wise physician question whetherany important result had accrued to practical medicine from Harvey'sdiscovery of the circulation. But Anatomy, Physiology, and Pathologyhave received a new light from this novel method of contemplating theliving structures, which has had a vast influence in enabling thepractitioner at least to distinguish and predict the course ofdisease. We know as well what differences to expect in the habits ofa mucous and of a serous membrane, as what mineral substances to lookfor in the chalk or the coal measures. You have only to readCullen's description of inflammation of the lungs or of the bowels,and compare it with such as you may find in Laennec or Watson, to seethe immense gain which diagnosis and prognosis have derived fromgeneral anatomy.

The second new method of studying the human structure, beginning withthe labors of Scarpa, Burns, and Colles, grew up principally duringthe first third of this century. It does not deal with organs, asdid the earlier anatomists, nor with tissues, after the manner ofBichat. It maps the whole surface of the body into an arbitrarynumber of regions, and studies each region successively from thesurface to the bone, or beneath it. This hardly deserves the name ofa science, although Velpeau has dignified it with that title, but itfurnishes an admirable practical way for the surgeon who has tooperate on a particular region of the body to study that region. Ifwe are buying a farm, we are not content with the State map or ageological chart including the estate in question. We demand anexact survey of that particular property, so that we may know what weare dealing with. This is just what regional, or, as it is sometimescalled, surgical anatomy, does for the surgeon with reference to thepart on which his skill is to be exercised. It enables him to seewith the mind's eye through the opaque tissues down to the bone onwhich they lie, as if the skin were transparent as the cornea, andthe organs it covers translucent as the gelatinous pulp of a medusa.

It is curious that the Japanese should have anticipated Europe in akind of rude regional anatomy. I have seen a manikin of Japanesemake traced all over with lines, and points marking theirintersection. By this their doctors are guided in the performance ofacupuncture, marking the safe places to thrust in needles, as we buoyout our ship-channels, and doubtless indicating to learned eyes thespots where incautious meddling had led to those little accidents ofshipwreck to which patients are unfortunately liable.

A change of method, then, has given us General and Regional Anatomy.These, too, have been worked so thoroughly, that, if not exhausted,they have at least become to a great extent fixed and positivebranches of knowledge. But the first of them, General Anatomy, wouldnever, have reached this positive condition but for the introductionof that, instrument which I have mentioned as the second great aid tomodern progress.

This instrument is the achromatic microscope. For the history of thesuccessive steps by which it became the effective scientificimplement we now possess, I must refer you to the work of Mr.Quekett, to an excellent article in the "Penny Cyclopaedia," or tothat of Sir David Brewster in the "Encyclopaedia Britannica." It isa most interesting piece of scientific history, which shows how theproblem which Biot in 1821 pronounced insolvable was in the course ofa few years practically solved, with a success equal to that whichDollond had long before obtained with the telescope. It is enoughfor our purpose that we are now in possession of an instrument freedfrom all confusions and illusions, which magnifies a thousanddiameters,--a million times in surface,--without serious distortionor discoloration of its object.

A quarter of a century ago, or a little more, an instructor would nothave hesitated to put John Bell's "Anatomy" and Bostock's"Physiology" into a student's hands, as good authority on theirrespective subjects. Let us not be unjust to either of theseauthors. John Bell is the liveliest medical writer that I canremember who has written since the days of delightful old AmbroisePare. His picturesque descriptions and bold figures are as good nowas they ever were, and his book can never become obsolete. Butlisten to what John Bell says of the microscope:

"Philosophers of the last age had been at infinite pains to find theultimate fibre of muscles, thinking to discover its properties in itsform; but they saw just in proportion to the glasses which they used,or to their practice and skill in that art, which is now almostforsaken."

Dr. Bostock's work, neglected as it is, is one which I value veryhighly as a really learned compilation, full of original references.But Dr. Bostock says: "Much as the naturalist has been indebted tothe microscope, by bringing into view many beings of which he couldnot otherwise have ascertained the existence, the physiologist hasnot yet derived any great benefit from the instrument."

These are only specimens of the manner in which the microscope andits results were generally regarded by the generation just precedingour own.

I have referred you to the proper authorities for the account ofthose improvements which about the year 1830 rendered the compoundmicroscope an efficient and trustworthy instrument. It was now forthe first time that a true general anatomy became possible. As earlyas 1816 Treviranus had attempted to resolve the tissues, of whichBichat had admitted no less than twenty-one, into their simplemicroscopic elements. How could such an attempt succeed, Henle wellasks, at a time when the most extensively diffused of all thetissues, the areolar, was not at all understood? All that methodcould do had been accomplished by Bichat and his followers. It wasfor the optician to take the next step. The future of anatomy andphysiology, as an enthusiastic micrologist of the time said, was inthe hands of Messrs. Schieck and Pistor, famous opticians of Berlin.

In those earlier days of which I am speaking, all the points ofminute anatomy were involved in obscurity. Some found globuleseverywhere, some fibres. Students disputed whether the conjunctivaextended over the cornea or not, and worried themselves over Gaultierde Claubry's stratified layers of the skin, or Breschet'sblennogenous and chromatogenous organs. The dartos was a puzzle, thecentral spinal canal a myth, the decidua clothed in fable as much asthe golden fleece. The structure of bone, now so beautifully madeout,--even that of the teeth, in which old Leeuwenhoek, peeping withhis octogenarian eyes through the minute lenses wrought with his ownhands, had long ago seen the "pipes," as he called them,--was hardlyknown at all. The minute structure of the viscera lay in the mistsof an uncertain microscopic vision. The intimate recesses of theanimal system were to the students of anatomy what the anterior ofAfrica long was to geographers, and the stories of microscopicexplorers were as much sneered at as those of Bruce or Du Chailly,and with better reason.

Now what have we come to in our own day? In the first place, theminute structure of all the organs has been made out in the mostsatisfactory way. The special arrangements of the vessels and theducts of all the glands, of the air-tubes and vesicles of the lungs,of the parts which make up the skin and other membranes, all thedetails of those complex parenchymatous organs which had confoundedinvestigation so long, have been lifted out of the invisible into thesight of all observers. It is fair to mention here, that we owe agreat deal to the art of minute injection, by which we are enabled totrace the smallest vessels in the midst of the tissues where they aredistributed. This is an old artifice of anatomists. The famousRuysch, who died a hundred and thirty years ago, showed that each ofthe viscera has its terminal vessels arranged in its own peculiarway; the same fact which you may see illustrated in Gerber's figuresafter the minute injections of Berres. I hope to show you manyspecimens of this kind in the microscope, the work of English andAmerican hands. Professor Agassiz allows me also to make use of avery rich collection of injected preparations sent him by ProfessorHyrtl, formerly of Prague, now of Vienna, for the proper exhibitionof which I had a number of microscopes made expressly, by Mr. Grunow,during the past season. All this illustrates what has been done forthe elucidation of the intimate details of formation of the organs.

But the great triumph of the microscope as applied to anatomy hasbeen in the resolution of the organs and the tissues into theirsimple constituent anatomical elements. It has taken up generalanatomy where Bichat left it. He had succeeded in reducing thestructural language of nature to syllables, if you will permit me touse so bold an image. The microscopic observers who have come afterhim have analyzed these into letters, as we may call them,--thesimple elements by the combination of which Nature spells outsuccessively tissues, which are her syllables, organs which are herwords, systems which are her chapters, and so goes on from the simpleto the complex, until she binds up in one living whole that wondrousvolume of power and wisdom which we call the human body.

The alphabet of the organization is so short and simple, that I willrisk fatiguing your attention by repeating it, according to the planI have long adopted.

A. Cells, either floating, as in the blood, or fixed, like those inthe cancellated structure of bone, already referred to. Verycommonly they have undergone a change of figure, most frequently aflattening which reduces them to scales, as in the epidermis and theepithelium.

B. Simple, translucent, homogeneous solid, such as is found at theback of the cornea, or forming the intercellular substance ofcartilage.

C. The white fibrous element, consisting of very delicate, tenaciousthreads. This is the long staple textile substance of the body. Itis to the organism what cotton is pretended to be to our SouthernStates. It pervades the whole animal fabric as areolar tissue, whichis the universal packing and wrapping material. It forms theligaments which bind the whole frame-work together. It furnishes thesinews, which are the channels of power. It enfolds every muscle.It wraps the brain in its hard, insensible folds, and the heartitself beats in a purse that is made of it.

D. The yellow elastic, fibrous element, the caoutchouc of the animalmechanism, which pulls things back into place, as the India-rubberband shuts the door we have opened.

E. The striped muscular fibre,--the red flesh, which shortens itselfin obedience to the will, and thus produces all voluntary activemotion.

F. The unstriped muscular fibre, more properly the fusiform-cellfibre, which carries on the involuntary internal movements.

G. The nerve-cylinder, a glassy tube, with a pith of some firmness,which conveys sensation to the brain and the principle which inducesmotion from it.

H. The nerve-corpuscle, the centre of nervous power.

I. The mucous tissue, as Virchow calls it, common in embryonicstructures, seen in the vitreous humor of the adult.

To these add X, granules, of indeterminate shape and size, Y, forinorganic matters, such as the salts of bone and teeth, and Z, tostand as a symbol of the fluids, and you have the letters of what Ihave ventured to call the alphabet of the body.

But just as in language certain diphthongs and syllables arefrequently recurring, so we have in the body certain secondary andtertiary combinations, which we meet more frequently than thesolitary elements of which they are composed.

Thus A B, or a collection of cells united by simple structurelesssolid, is seen to be extensively employed in the body under the nameof cartilage. Out of this the surfaces of the articulations and thesprings of the breathing apparatus are formed. But when Nature cameto the buffers of the spinal column (intervertebral disks) and thewashers of the joints (semilunar fibrocartilages of the knee, etc.),she required more tenacity than common cartilage possessed. What didshe do? What does man do in a similar case of need? I need hardlytell you. The mason lays his bricks in simple mortar. But theplasterer works some hair into the mortar which he is going to lay inlarge sheets on the walls. The children of Israel complained thatthey had no straw to make their bricks with, though portions of itmay still be seen in the crumbling pyramid of Darshour, which theyare said to have built. I visited the old house on Witch Hill inSalem a year or two ago, and there I found the walls coated with clayin which straw was abundantly mingled;--the old Judaizing witch-hangers copied the Israelites in a good many things. The Chinese andthe Corsicans blend the fibres of amianthus in their pottery to giveit tenacity. Now to return to Nature. To make her buffers andwashers hold together in the shocks to which they would be subjected,she took common cartilage and mingled the white fibrous tissue withit, to serve the same purpose as the hair in the mortar, the straw inthe bricks and in the plaster of the old wall, and the amianthus inthe earthen vessels. Thus we have the combination A B C, or fibro-cartilage. Again, the bones were once only gristle or cartilage, AB. To give them solidity they were infiltrated with stone, in theform of salts of lime, an inorganic element, so that bone would bespelt out by the letters A, B, and Y.

If from these organic syllables we proceed to form organic words, weshall find that Nature employs three principal forms; namely,Vessels, Membranes, and Parenchyma, or visceral tissue. The mostcomplex of them can be resolved into a combination of these fewsimple anatomical constituents.

Passing for a moment into the domain of PATHOLOGICAL ANATOMY, we findthe same elements in morbid growths that we have met with in normalstructures. The pus-corpuscle and the white blood-corpuscle can onlybe distinguished by tracing them to their origin. A frequent form ofso-called malignant disease proves to be only a collection of alteredepithelium-cells. Even cancer itself has no specific anatomicalelement, and the diagnosis of a cancerous tumor by the microscope,though tolerably sure under the eye of an expert, is based uponaccidental, and not essential points,--the crowding together of theelements, the size of the cell-nuclei, and similar variablecharacters.

Let us turn to PHYSIOLOGY. The microscope, which has made a newscience of the intimate structure of the organs, has at the same timecleared up many uncertainties concerning the mechanism of the specialfunctions. Up to the time of the living generation of observers,Nature had kept over all her inner workshops the forbiddinginscription, No Admittance! If any prying observer ventured to spythrough his magnifying tubes into the mysteries of her glands andcanals and fluids, she covered up her work in blinding mists andbewildering halos, as the deities of old concealed their favoredheroes in the moment of danger.

Science has at length sifted the turbid light of her lenses, andblanched their delusive rainbows.

Anatomy studies the organism in space. Physiology studies it also intime. After the study of form and composition follows close that ofaction, and this leads us along back to the first moment of the germ,and forward to the resolution of the living frame into its lifelesselements. In this way Anatomy, or rather that branch of it which wecall Histology, has become inseparably blended with the study offunction. The connection between the science of life and that ofintimate structure on the one hand, and composition on the other, isillustrated in the titles of two recent works of remarkableexcellence,--"the Physiological Anatomy" of Todd and Bowman, and the"Physiological Chemistry" of Lehmann.

Let me briefly recapitulate a few of our acquisitions in Physiology,due in large measure to our new instruments and methods of research,and at the same time indicate the limits which form the permanent orthe temporary boundaries of our knowledge. I will begin with thelargest fact and with the most absolute and universally encounteredlimitation.

The "largest truth in Physiology" Mr. Paget considers to be "thedevelopment of ova through multiplication and division of theircells." I would state it more broadly as the agency of the cell inall living processes. It seems at present necessary to abandon theoriginal idea of Schwann, that we can observe the building up of acell from the simple granules of a blastema, or formative fluid. Theevidence points rather towards the axiom, Omnis cellula a cellula;that is, the germ of a new cell is always derived from a preexistingcell. The doctrine of Schwann, as I remarked long ago (1844), runsparallel with the nebular theory in astronomy, and they may yet standor fall together.

As we have seen Nature anticipating the plasterer in fibro-cartilage,so we see her beforehand with the glassblower in her dealings withthe cell. The artisan blows his vitreous bubbles, large or small, tobe used afterwards as may be wanted. So Nature shapes her hyalinevesicles and modifies them to serve the needs of the part where theyare found. The artisan whirls his rod, and his glass bubble becomesa flattened disk, with its bull's-eye for a nucleus. These lips ofours are all glazed with microscopic tiles formed of flattened cells,each one of them with its nucleus still as plain and relatively asprominent, to the eye of the microscopist, as the bull's-eye in theold-fashioned windowpane. Everywhere we find cells, modified orunchanged. They roll in inconceivable multitudes (five millions andmore to the cubic millimetre, according to Vierordt) as blood-disksthrough our vessels. A close-fitting mail of flattened cells coatsour surface with a panoply of imbricated scales (more than twelvethousand millions), as Harting has computed, as true a defence againstour enemies as the buckler of the armadillo or the carapace of thetortoise against theirs. The same little protecting organs pave allthe great highways of the interior system. Cells, again, presideover the chemical processes which elaborate the living fluids; theychange their form to become the agents of voluntary and involuntarymotion; the soul itself sits on a throne of nucleated cells, andflashes its mandates through skeins of glassy filaments which oncewere simple chains of vesicles. And, as if to reduce the problem ofliving force to its simplest expression, we see the yolk of atransparent egg dividing itself in whole or in part, and againdividing and subdividing, until it becomes a mass of cells, out ofwhich the harmonious diversity of the organs arranges itself, worm orman, as God has willed from the beginning.

This differentiation having been effected, each several part assumesits special office, having a life of its own adjusted to that ofother parts and the whole. "Just as a tree constitutes a massarranged in a definite manner, in which, in every single part, in theleaves as in the root, in the trunk as in the blossom, cells arediscovered to be the ultimate elements, so is it also with the formsof animal life. Every animal presents itself as a sum of vitalunities, every one of which manifests all the characteristics oflife."

The mechanism is as clear, as unquestionable, as absolutely settledand universally accepted, as the order of movement of the heavenlybodies, which we compute backward to the days of the observatories onthe plains of Shinar, and on the faith of which we regulate themovements of war and trade by the predictions of our ephemeris.

The mechanism, and that is all. We see the workman and the tools,but the skill that guides the work and the power that performs it areas invisible as ever. I fear that not every listener took thesignificance of those pregnant words in the passage I quoted fromJohn Bell,--"thinking to discover its properties in its form." Wehave discovered the working bee in this great hive of organization.We have detected the cell in the very act of forming itself from anucleus, of transforming itself into various tissues, of selectingthe elements of various secretions. But why one cell becomes nerveand another muscle, why one selects bile and another fat, we can nomore pretend to tell, than why one grape sucks out of the soil thegenerous juice which princes hoard in their cellars, and another thewine which it takes three men to drink,--one to pour it down, anotherto swallow it, and a third to hold him while it is going down.Certain analogies between this selecting power and the phenomena ofendosmosis in the elective affinities of chemistry we can find, butthe problem of force remains here, as everywhere, unsolved andinsolvable.

Do we gain anything by attempting to get rid of the idea of a specialvital force because we find certain mutually convertible relationsbetween forces in the body and out of it? I think not, any more thanwe should gain by getting rid of the idea and expression Magnetismbecause of its correlation with electricity. We may concede theunity of all forms of force, but we cannot overlook the fixeddifferences of its manifestations according to the conditions underwhich it acts. It is a mistake, however, to think the mystery isgreater in an organized body than in any other. We see a stone fallor a crystal form, and there is nothing stranger left to wonder at,for we have seen the Infinite in action.

Just so far as we can recognize the ordinary modes of operation ofthe common forces of nature,--gravity, cohesion, elasticity,transudation, chemical action, and the rest,--we see the so-calledvital acts in the light of a larger range of known facts and familiaranalogies. Matteuecci's well-remembered lectures contain many andstriking examples of the working of physical forces in physiologicalprocesses. Wherever rigid experiment carries us, we are safe infollowing this lead; but the moment we begin to theorize beyond ourstrict observation, we are in danger of falling into those mechanicalfollies which true science has long outgrown.

Recognizing the fact, then, that we have learned nothing but themachinery of life, and are no nearer to its essence, what is it thatwe have gained by this great discovery of the cell formation andfunction?

It would have been reward enough to learn the method Nature pursuesfor its own sake. If the sovereign Artificer lets us into his ownlaboratories and workshops, we need not ask more than the privilegeof looking on at his work. We do not know where we now stand in thehierarchy of created intelligences. We were made a little lower thanthe angels. I speak it not irreverently; as the lower animalssurpass man in some of their attributes, so it may be that not everyangel's eye can see as broadly and as deeply into the material worksof God as man himself, looking at the firmament through an equatorialof fifteen inches' aperture, and searching into the tissues with atwelfth of an inch objective.

But there are other positive gains of a more practical character.Thus we are no longer permitted to place the seat of the livingactions in the extreme vessels, which are only the carriers fromwhich each part takes what it wants by the divine right of theomnipotent nucleated cell. The organism has become, in the wordsalready borrowed from Virchow, "a sum of vital unities." Thestrictum and laxum, the increased and diminished action of thevessels, out of which medical theories and methods of treatment havegrown up, have yielded to the doctrine of local cell-communities,belonging to this or that vascular district, from which they helpthemselves, as contractors are wont to do from the national treasury.

I cannot promise to do more than to select a few of the points ofcontact between our ignorance and our knowledge which presentparticular interest in the existing state of our physiologicalacquisitions. Some of them involve the microscopic discoveries ofwhich I have been speaking, some belong to the domain of chemistry,and some have relations with other departments of physical science.

If we should begin with the digestive function, we should find thatthe long-agitated question of the nature of the acid of the gastricjuice is becoming settled in favor of the lactic. But the wholesolvent agency of the digestive fluid enters into the category ofthat exceptional mode of action already familiar to us in chemistryas catalysis. It is therefore doubly difficult of explanation;first, as being, like all reactions, a fact not to be accounted forexcept by the imaginative appeal to "affinity," and secondly, asbeing one of those peculiar reactions provoked by an element whichstands outside and looks on without compromising itself.

The doctrine of Mulder, so widely diffused in popular and scientificbelief, of the existence of a common base of all albuminoussubstances, the so-called protein, has not stood the test of rigorousanalysis. The division of food into azotized and non-azotized is nodoubt important, but the attempt to show that the first only isplastic or nutritive, while the second is simply calorifacient, orheat-producing, fails entirely in the face of the facts revealed bythe study of man in different climates, and of numerous experimentsin the feeding of animals. I must return to this subject inconnection with the respiratory function.

The sugar-making faculty of the liver is another "catalytic" mystery,as great as the rest of them, and no greater. Liver-tissue bringssugar out of the blood, or out of its own substance;--why?

Quia est in eo Virtus saccharitiva.

Just what becomes of the sugar beyond the fact of its disappearancebefore it can get into the general circulation and sweeten ourtempers, it is hard to say.

The pancreatic fluid makes an emulsion of the fat contained in ourfood, but just how the fatty particles get into the villi we mustleave Brucke and Kolliker to settle if they can.

No one has shown satisfactorily the process by which the blood-corpuscles are formed out of the lymph-corpuscles, nor what becomesof them. These two questions are like those famous householdpuzzles,--Where do the flies come from? and, Where do the pins goto?

There is a series of organs in the body which has long puzzledphysiologists,--organs of glandular aspect, but having no ducts,--thespleen, the thyroid and thymus bodies, and the suprarenal capsules.We call them vascular glands, and we believe that they elaboratecolored and uncolored blood-cells; but just what changes they effect,and just how they effect them, it has proved a very difficult matterto determine. So of the noted glandules which form Peyer's patches,their precise office, though seemingly like those of the lymphaticglands, cannot be positively assigned, so far as I know, at thepresent time. It is of obvious interest to learn it with referenceto the pathology of typhoid fever. It will be remarked that thecoincidence of their changes in this disease with enlargement of thespleen suggests the idea of a similarity of function in these twoorgans.

The theories of the production of animal heat, from the times ofBlack, Lavoisier, and Crawford to those of Liebig, are familiar toall who have paid any attention to physiological studies. Thesimplicity of Liebig's views, and the popular form in which they havebeen presented, have given them wide currency, and incorporated themin the common belief and language of our text-books. Directoxidation or combustion of the carbon and hydrogen contained in thefood, or in the tissues themselves; the division of alimentarysubstances into respiratory, or non-azotized, and azotized,--thesedoctrines are familiar even to the classes in our high-schools. Butthis simple statement is boldly questioned. Nothing proves thatoxygen combines (in the system) with hydrogen and carbon inparticular, rather than with sulphur and azote. Such is the well-grounded statement of Robin and Verdeil. "It is very probable thatanimal heat is entirely produced by the chemical actions which takeplace in the organism, but the phenomenon is too complex to admit ofour calculating it according to the quality of oxygen consumed."These last are the words of Regnault, as cited by Mr. Lewes, whoseintelligent discussion of this and many of the most interestingphysiological problems I strongly recommend to your attention.

This single illustration covers a wider ground than the specialfunction to which it belongs. We are learning that the chemistry ofthe body must be studied, not simply by its ingesta and egesta, butthat there is a long intermediate series of changes which must beinvestigated in their own light, under their own special conditions.The expression "sum of vital unities" applies to the chemicalactions, as well as to other actions localized in special parts; andwhen the distinguished chemists whom I have just cited entitle theirwork a treatise on the immediate principles of the body, they onlyindicate the nature of that profound and subtile analysis which musttake the place of all hasty generalizations founded on a comparisonof the food with residual products.

I will only call your attention to the fact, that the exceptionalphenomenon of the laboratory is the prevailing law of the organism.Nutrition itself is but one great catalytic process. As the bloodtravels its rounds, each part selects its appropriate element andtransforms it to its own likeness. Whether the appropriating agentbe cell or nucleus, or a structureless solid like the intercellularsubstance of cartilage, the fact of its presence determines theseparation of its proper constituents from the circulating fluid, sothat even when we are wounded bone is replaced by bone, skin by skin,and nerve by nerve.

It is hardly without a smile that we resuscitate the old question ofthe 'vis insita' of the muscular fibre, so famous in the discussions ofHaller and his contemporaries. Speaking generally, I think we maysay that Haller's doctrine is the one now commonly received; namely,that the muscles contract in virtue of their own inherent endowments.It is true that Kolliker says no perfectly decisive fact has beenbrought forward to prove that the striated muscles contract with.out having been acted on by nerves. Yet Mr. Bowman's observations onthe contraction of isolated fibres appear decisive enough (unless weconsider them invalidated by Dr. Lionel Beale's recent researches),tending to show that each elementary fibre is supplied with nerves;and as to the smooth muscular fibres, we have Virchow's statementrespecting the contractility of those of the umbilical cord, wherethere is not a trace of any nerves.

In the investigation of the nervous system, anatomy and physiologyhave gone hand in hand. It is very singular that so important, andseemingly simple, a fact as the connection of the nerve-tubes, attheir origin or in their course, with the nerve-cells, should have solong remained open to doubt, as you may see that it did by referringto the very complete work of Sharpey and Quain (edition of 1849), thehistological portion of which is cordially approved by Kollikerhimself.

Several most interesting points of the minute anatomy of the nervouscentres have been laboriously and skilfully worked out by a recentgraduate of this Medical School, in a monograph worthy to stand inline with those of Lockhart Clarke, Stilling, and Schroder van derKolk. I have had the privilege of examining and of showing some ofyou a number of Dr. Dean's skilful preparations. I have no space togive even an abstract of his conclusions. I can only refer to hisproof of the fact, that a single cell may send its processes intoseveral different bundles of nerve-roots, and to his demonstration ofthe curved ascending and descending fibres from the posteriornerveroots, to reach what he has called the longitudinal columns ofthe cornea. I must also mention Dr. Dean's exquisite microscopicphotographs from sections of the medulla oblongata, which appear tome to promise a new development, if not a new epoch, in anatomicalart.

It having been settled that the nerve-tubes can very commonly betraced directly to the nerve-cells, the object of all the observersin this department of anatomy is to follow these tubes to theirorigin. We have an infinite snarl of telegraph wires, and we may bereasonably sure, that, if we can follow them up, we shall find eachof them ends in a battery somewhere. One of the most interestingproblems is to find the ganglionic origin of the great nerves of themedulla oblongata, and this is the end to which, by the aid of themost delicate sections, colored so as to bring out their details,mounted so as to be imperishable, magnified by the best instruments,and now self-recorded in the light of the truth-telling sunbeam, ourfellow-student is making a steady progress in a labor which I thinkbids fair to rank with the most valuable contributions to histologythat we have had from this side of the Atlantic.

It is interesting to see how old questions are incidentally settledin the course of these new investigations. Thus, Mr. Clarke'sdissections, confirmed by preparations of Mr. Dean's which I havemyself examined, placed the fact of the decussation of the pyramids--denied by Haller, by Morgagni, and even by Stilling--beyond doubt.So the spinal canal, the existence of which, at least in the adult,has been so often disputed, appears as a coarse and unequivocalanatomical fact in many of the preparations referred to.

While these studies of the structure of the cord have been going on,the ingenious and indefatigable Brown-Sequard has been investigatingthe functions of its different parts with equal diligence. Themicroscopic anatomists had shown that the ganglionic corpuscles ofthe gray matter of the cord are connected with each other by theirprocesses, as well as with the nerve-roots. M. Brown-Sequard hasproved by numerous experiments that the gray substance transmitssensitive impressions and muscular stimulation. The obliqueascending and descending fibres from the posterior nerve-roots,joining the "longitudinal columns of the cornua," account for theresults of Brown-Sequard's sections of the posterior columns. Thephysiological experimenter has also made it evident that thedecussation of the conductors of sensitive impressions has its seatin the spinal core, and not in the encephalon, as had been supposed.Not less remarkable than these results are the facts, which I withothers of my audience have had the opportunity of observing, as shownby M. Brown-Sequard, of the artificial production of epilepsy inanimals by injuring the spinal cord, and the induction of theparoxysm by pinching a certain portion of the skin. I would alsocall the student's attention to his account of the relations of thenervous centres to nutrition and secretion, the last of whichrelations has been made the subject of an extended essay by ourfellow countryman, Dr. H. F. Campbell of Georgia.

The physiology of the spinal cord seems a simple matter as you studyit in Longet. The experiments of Brown-Sequard have shown theproblem to be a complex one, and raised almost as many doubts as theyhave solved questions; at any rate, I believe all lecturers onphysiology agree that there is no part of their task they dread somuch as the analysis of the evidence relating to the special officesof the different portions of the medulla spinalis. In the brain weare sure that we do not know how to localize functions; in the spinalcord, we think we do know something; but there are so many anomalies,and seeming contradictions, and sources of fallacy, that beyond thefacts of crossed paralysis of sensation, and the conducting agency ofthe gray substance, I am afraid we retain no cardinal principlesdiscovered since the development of the reflex function took itsplace by Sir Charles Bell's great discovery.

By the manner in which I spoke of the brain, you will see that I amobliged to leave phrenology sub Jove,--out in the cold,--as not oneof the household of science. I am not one of its haters; on thecontrary, I am grateful for the incidental good it has done. I loveto amuse myself in its plaster Golgothas, and listen to the glibprofessor, as he discovers by his manipulations

"All that disgraced my betters met in me."

I loved of old to see square-headed, heavy-jawed Spurzheim make abrain flower out into a corolla of marrowy filaments, as Vieussenshad done before him, and to hear the dry-fibred but human-heartedGeorge Combe teach good sense under the disguise of his equivocalsystem. But the pseudo-sciences, phrenology and the rest, seem to meonly appeals to weak minds and the weak points of strong ones. Thereis a pica or false appetite in many intelligences; they take to oddfancies in place of wholesome truth, as girls gnaw at chalk andcharcoal. Phrenology juggles with nature. It is so adjusted as tosoak up all evidence that helps it, and shed all that harms it. Itcrawls forward in all weathers, like Richard Edgeworth's hygrometer.It does not stand at the boundary of our ignorance, it seems to me,but is one of the will-o'-the-wisps of its undisputed central domainof bog and quicksand. Yet I should not have devoted so many words toit, did I not recognize the light it has thrown on human actions byits study of congenital organic tendencies. Its maps of the.surface of the head are, I feel sure, founded on a delusion, but itsstudies of individual character are always interesting andinstructive.

The "snapping-turtle" strikes after its natural fashion when it firstcomes out of the egg. Children betray their tendencies in their wayof dealing with the breasts that nourish them; nay, lean venture toaffirm, that long before they are born they teach their motherssomething of their turbulent or quiet tempers.

"Castor gaudet equis, ovo proanatus eodem Pugnis."

Strike out the false pretensions of phrenology; call it anthropology;let it study man the individual in distinction from man theabstraction, the metaphysical or theological lay-figure; and itbecomes "the proper study of mankind," one of the noblest and mostinteresting of pursuits.

The whole physiology of the nervous system, from the simplestmanifestation of its power in an insect up to the supreme act of thehuman intelligence working through the brain, is full of the mostdifficult yet profoundly interesting questions. The singularrelations between electricity and nerve-force, relations which it hasbeen attempted to interpret as meaning identity, in the face ofpalpable differences, require still more extended studies. You maybe interested by Professor Faraday's statement of his opinion on thematter. "Though I am not satisfied that the nervous fluid is onlyelectricity, still I think that the agent in the nervous system maybean inorganic force; and if there be reason for supposing thatmagnetism is a higher relation of force than electricity, so it maywell be imagined that the nervous power may be of a still moreexalted character, and yet within the reach of experiment."

In connection with this statement, it is interesting to refer to theexperiments of Helmholtz on the rapidity of transmission of thenervous actions. The rate is given differently in Valentin's reportof these experiments and in that found in the "Scientific Annual" for1858. One hundred and eighty to three hundred feet per second is therate of movement assigned for sensation, but all such results must bevery vaguely approximative. Boxers, fencers, players at the Italiangame of morn, "prestidigitators," and all who depend for theirsuccess on rapidity of motion, know what differences there are in thepersonal equation of movement.

Reflex action, the mechanical sympathy, if I may so call it, ofdistant parts; Instinct, which is crystallized intelligence,--anabsolute law with its invariable planes and angles introduced intothe sphere of consciousness, as raphides are inclosed in the livingcells of plants; Intellect,--the operation of the thinking principlethrough material organs, with an appreciable waste of tissue in everyact of thought, so that our clergymen's blood has more phosphates toget rid of on Monday than on any other day of the week; Will,--theoretically the absolute determining power, practically limited indifferent degrees by the varying organization of races andindividuals, annulled or perverted by different ill-understoodorganic changes; on all these subjects our knowledge is in itsinfancy, and from the study of some of them the interdict of theVatican is hardly yet removed.

I must allude to one or two points in the histology and physiology ofthe organs of sense. The anterior continuation of the retina beyondthe ora serrata has been a subject of much discussion. If H. Mullerand Kolliker can be relied upon, this question is settled byrecognizing that a layer of cells, continued from the retina, passesover the surface of the zonula Zinnii, but that no proper nervouselement is so prolonged forward.

I observe that Kolliker calls the true nervous elements of the retina"the layer of gray cerebral substance." In fact, the ganglioniccorpuscles of each eye may be considered as constituting a littlebrain, connected with the masses behind by the commissure, commonlycalled the optic nerve. We are prepared, therefore, to find thesetwo little brains in the most intimate relations with each other, aswe find the cerebral hemispheres. We know that they are directlyconnected by fibres that arch round through the chiasma.

I mention these anatomical facts to introduce a physiologicalobservation of my own, first announced in one of the lectures beforethe Medical Class, subsequently communicated to the American Academyof Arts and Sciences, and printed in its "Transactions" for February14, 1860. I refer to the apparent transfer of impressions from oneretina to the other, to which I have given the name reflex vision.The idea was suggested to me in consequence of certain effectsnoticed in employing the stereoscope. Professor William B. Rodgershas since called the attention of the American Scientific Associationto some facts bearing on the subject, and to a very curiousexperiment of Leonardo da Vinci's, which enables the observer to lookthrough the palm of his hand (or seem to), as if it had a hole boredthrough it. As he and others hesitated to accept my explanation, Iwas not sorry to find recently the following words in the"Observations on Man" of that acute observer and thinker, DavidHartley. "An impression made on the right eye alone by a singleobject may propagate itself into the left, and there raise up animage almost equal in vividness to itself; and consequently when wesee with one eye only, we may, however, have pictures in both eyes."Hartley, in 1784, had anticipated many of the doctrines which havesince been systematized into the theory of reflex actions, and withwhich I have attempted to associate this act of reflex vision. Mysixth experiment, however, in the communication referred to, appearsto me to be a crucial one, proving the correctness of my explanation,and I am not aware that it has been before instituted.

Another point of great interest connected with the physiology ofvision, and involved for a long time in great obscurity, is that ofthe adjustment of the eye to different distances. Dr. Clay Wallaceof New York, who published a very ingenious little book on the eyeabout twenty years ago, with vignettes reminding one of Bewick, wasamong the first, if not the first, to describe the ciliary muscle, towhich the power of adjustment is generally ascribed. It isascertained, by exact experiment with the phacueidoscope, thataccommodation depends on change of form of the crystalline lens.Where the crystalline is wanting, as Mr. Ware long ago taught, nopower of accommodation remains. The ciliary muscle is generallythought to effect the change of form of the crystalline. The powerof accommodation is lost after the application of atropine, inconsequence, as is supposed, of the paralysis of this muscle. This,I believe, is the nearest approach to a demonstration we have on thispoint.

I have only time briefly to refer to Professor Draper's mostingenious theory as to the photographic nature of vision, for anaccount of which I must refer to his original and interestingTreatise on Physiology.

It were to be wished that the elaborate and very interestingresearches of the Marquis Corti, which have revealed such singularcomplexity of structure in the cochlea of the ear, had done more toclear up its doubtful physiology; but I am afraid we have nothing buthypotheses for the special part it plays in the act of hearing, andthat we must say the same respecting the office of the semicircularcanals.

The microscope has achieved some of its greatest triumphs in teachingus the changes which occur in the development of the embryo. No moreinteresting discovery stands recorded in the voluminous literature ofthis subject than the one originally announced by Martin Barry,afterwards discredited, and still later confirmed by Mr. Newport andothers; namely the fact that the fertilizing filament reaches theinterior of the ovum in various animals;--a striking parallel to theaction of the pollen-tube in the vegetable. But beyond themechanical facts all is mystery in the movements of organization, asprofound as in the fall of a stone or the formation of a crystal.

To the chemist and the microscopist the living body presents the samedifficulties, arising from the fact that everything is in perpetualchange in the organism. The fibrine of the blood puzzles the one asmuch as its globules puzzle the other. The difference between thebranches of science which deal with space only, and those which dealwith space and time, is this: we have no glasses that can magnifytime. The figure I here show you a was photographed from an object(pleurosigma angulatum) magnified a thousand diameters, or presentinga million times its natural surface. This other figure of the sameobject, enlarged from the one just shown, is magnified seven thousanddiameters, or forty-nine million times in surface. When we can makethe forty-nine millionth of a second as long as its integer,physiology and chemistry will approach nearer the completeness ofanatomy.

Our reverence becomes more worthy, or, if you will, less unworthy ofits Infinite Object in proportion as our intelligence is lifted andexpanded to a higher and broader understanding of the Divine methodsof action. If Galen called his heathen readers to admire, the power,the wisdom, the providence, the goodness of the "Framer of the animalbody,"--if Mr. Boyle, the student of nature, as Addison and thatfriend of his who had known him for forty years tell us, neveruttered the name of the Supreme Being without making a distinct pausein his speech, in token of his devout recognition of its awfulmeaning,--surely we, who inherit the accumulated wisdom of nearly twohundred years since the time of the British philosopher, and ofalmost two thousand since the Greek physician, may well lift ourthoughts from the works we study to their great Artificer. Thesewonderful discoveries which we owe to that mighty little instrument,the telescope of the inner firmament with all its included worlds;these simple formulae by which we condense the observations of ageneration in a single axiom; these logical analyses by which wefence out the ignorance we cannot reclaim, and fix the limits of ourknowledge,--all lead us up to the inspiration of the Almighty, whichgives understanding to the world's great teachers. To fear scienceor knowledge, lest it disturb our old beliefs, is to fear the influxof the Divine wisdom into the souls of our fellow-men; for what isscience but the piecemeal revelation,--uncovering,--of the plan ofcreation, by the agency of those chosen prophets of nature whom Godhas illuminated from the central light of truth for that singlepurpose?

The studies which we have glanced at are preliminary in youreducation to the practical arts which make use of them,--the arts ofhealing,--surgery and medicine. The more you examine the structureof the organs and the laws of life, the more you will find howresolutely each of the cell-republics which make up the E pluribusunum of the body maintains its independence. Guard it, feed it, airit, warm it, exercise or rest it properly, and the working elementswill do their best to keep well or to get well. What do we do withailing vegetables? Dr. Warren, my honored predecessor in this chair,bought a country-place, including half of an old orchard. A fewyears afterwards I saw the trees on his side of the fence looking ingood health, while those on the other side were scraggy andmiserable. How do you suppose this change was brought about? Bywatering them with Fowler's solution? By digging in calomel freelyabout their roots? Not at all; but by loosening the soil round them,and supplying them with the right kind of food in fitting quantities.

Now a man is not a plant, or, at least, he is a very curious one, forhe carries his soil in his stomach, which is a kind--of portableflower-pot, and he grows round it, instead of out of it. He has,besides, a singularly complex nutritive apparatus and a nervoussystem. But recollect the doctrine already enunciated in thelanguage of Virchow, that an animal, like a tree, is a sum of vitalunities, of which the cell is the ultimate element. Every healthycell, whether in a vegetable or an animal, necessarily performs itsfunction properly so long as it is supplied with its proper materialsand stimuli. A cell may, it is true, be congenitally defective, inwhich case disease is, so to speak, its normal state. But iforiginally sound and subsequently diseased, there has certainly beensome excess, deficiency, or wrong quality in the materials or stimuliapplied to it. You remove this injurious influence and substitute anormal one; remove the baked coal-ashes, for instance, from the rootsof a tree, and replace them with loam; take away the salt meat fromthe patient's table, and replace it with fresh meat and vegetables,and the cells of the tree or the man return to their duty.

I do not know that we ever apply to a plant any element which is nota natural constituent of the vegetable structure, except perhapsexternally, for the accidental purpose of killing parasites. Thewhole art of cultivation consists in learning the proper food andconditions of plants, and supplying them. We give them water,earths, salts of various kinds such as they are made of, with achance to help themselves to air and light. The farmer would belaughed at who undertook to manure his fields or his trees with asalt of lead or of arsenic. These elements are not constituents ofhealthy plants. The gardener uses the waste of the arsenic furnacesto kill the weeds in his walks.

If the law of the animal cell, and of the animal organism, which isbuilt up of such cells, is like that of the vegetable, we mightexpect that we should treat all morbid conditions of any of the vitalunities belonging to an animal in the same way, by increasing,diminishing, or changing its natural food or stimuli.

That is an aliment which nourishes; whatever we find in theorganism, as a constant and integral element, either forming part ofits structure, or one of the conditions of vital processes, that andthat only deserves the name of aliment. I see no reason,therefore, why iron, phosphate of lime, sulphur, should not beconsidered food for man, as much as guano or poudrette forvegetables. Whether one or another of them is best in any givencase,--whether they shall be taken alone or in combination, in largeor small quantities, are separate questions. But they are elementsbelonging to the body, and even in moderate excess will producelittle disturbance. There is no presumption against any of thisclass of substances, any more than against water or salt, providedthey are used in fitting combinations, proportions, and forms.

But when it comes to substances alien to the healthy system, whichnever belong to it as normal constituents, the case is verydifferent. There is a presumption against putting lead or arsenicinto the human body, as against putting them into plants, becausethey do not belong there, any more than pounded glass, which, it issaid, used to be given as a poison. The same thing is true ofmercury and silver. What becomes of these alien substances afterthey get into the system we cannot always tell. But in the case ofsilver, from the accident of its changing color under the influenceof light, we do know what happens. It is thrown out, in part atleast, under the epidermis, and there it remains to the patient'sdying day. This is a striking illustration of the difficulty whichthe system finds in dealing with non-assimilable elements, andjustifies in some measure the vulgar prejudice against mineralpoisons.

I trust the youngest student on these benches will not commit thechildish error of confounding a presumption against a particularclass of agents with a condemnation of them. Mercury, for instance,is alien to the system, and eminently disturbing in its influence.Yet its efficacy in certain forms of specific disease is acknowledgedby all but the most sceptical theorists. Even the esprit moqueur ofRicord, the Voltaire of pelvic literature, submits to the time-honored constitutional authority of this great panacea in the classof cases to which he has devoted his brilliant intelligence. Still,there is no telling what evils have arisen from the abuse of thismineral. Dr. Armstrong long ago pointed out some of them, and theyhave become matters of common notoriety. I am pleased, therefore,when I find so able and experienced a practitioner as Dr. Williams ofthis city proving that iritis is best treated without mercury, andDr. Vanderpoel showing the same thing to be true for pericarditis.

Whatever elements nature does not introduce into vegetables, thenatural food of all animal life,--directly of herbivorous, indirectlyof carnivorous animals,--are to be regarded with suspicion. Arsenic-eating may seem to improve the condition of horses for a time,--andeven of human beings, if Tschudi's stories can be trusted,--but itsoon appears that its alien qualities are at war with the animalorganization. So of copper, antimony, and other non-alimentarysimple substances; everyone of them is an intruder in the livingsystem, as much as a constable would be, quartered in our household.This does not mean that they may not, any of them, be called in for aspecial need, as we send for the constable when we have good reasonto think we have a thief under our roof; but a man's body is hiscastle, as well as his house, and the presumption is that we are tokeep our alimentary doors bolted against these perturbing agents.

Now the feeling is very apt to be just contrary to this. The habithas been very general with well-taught practitioners, to haverecourse to the introduction of these alien elements into the systemon the occasion of any slight disturbance. The tongue was a littlecoated, and mercury must be given; the skin was a little dry, and thepatient must take antimony. It was like sending for the constableand the posse comitatus when there is only a carpet to shake or arefuse-barrel to empty. [Dr. James Johnson advises persons not ailingto take five grains of blue pill with one or two of aloes twice aweek for three or four months in the year, with half a pint ofcompound decoction of sarsaparilla every day for the same period, topreserve health and prolong life. Pract. Treatise on Dis. ofLiver, etc. p. 272.] The constitution bears slow poisoning a greatdeal better than might be expected; yet the most intelligent men inthe profession have gradually got out of the habit of prescribingthese powerful alien substances in the old routine way. Mr. Metcalfwill tell you how much more sparingly they are given by ourpractitioners at the present time, than when he first inaugurated thenew era of pharmacy among us. Still, the presumption in favor ofpoisoning out every spontaneous reaction of outraged nature is notextinct in those who are trusted with the lives of their fellow-citizens. "On examining the file of prescriptions at the hospital, Idiscovered that they were rudely written, and indicated a treatment,as they consisted chiefly of tartar emetic, ipecacuanha, and epsomsalts, hardly favorable to the cure of the prevailing diarrhoea anddysenteries." In a report of a poisoning case now on trial, wherewe are told that arsenic enough was found in the stomach to producedeath in twenty-four hours, the patient is said to have been treatedby arsenic, phosphorus, bryonia, aconite, nux vomica, and muriaticacid,--by a practitioner of what school it may be imagined.

The traditional idea of always poisoning out disease, as we smoke outvermin, is now seeking its last refuge behind the wooden cannon andpainted port-holes of that unblushing system of false scientificpretences which I do not care to name in a discourse addressed to anaudience devoted to the study of the laws of nature in the light ofthe laws of evidence. It is extraordinary to observe that the systemwhich, by its reducing medicine to a name and a farce, has accustomedall who have sense enough to see through its thin artifices to theidea that diseases get well without being "cured," should now be themain support of the tottering poison-cure doctrine. It hasunquestionably helped to teach wise people that nature heals mostdiseases without help from pharmaceutic art, but it continues topersuade fools that art can arrest them all with its specifics.

It is worse than useless to attempt in any way to check the freestexpression of opinion as to the efficacy of any or all of the"heroic" means of treatment employed by practitioners of differentschools and periods. Medical experience is a great thing, but wemust not forget that there is a higher experience, which tries itsresults in a court of a still larger jurisdiction; that, namely, inwhich the laws of human belief are summoned to the witness-box, andobliged to testify to the sources of error which beset the medicalpractitioner. The verdict is as old as the father of medicine, whoannounces it in the words, "judgment is difficult." Physiciansdiffered so in his time, that some denied that there was any suchthing as an art of medicine.

One man's best remedies were held as mischievous by another. The artof healing was like soothsaying, so the common people said; "the samebird was lucky or unlucky, according as he flew to the right orleft."

The practice of medicine has undergone great changes within theperiod of my own observation. Venesection, for instance, has so fargone out of fashion, that, as I am told by residents of the New YorkBellevue and the Massachusetts General Hospitals, it is almostobsolete in these institutions, at least in medical practice. Theold Brunonian stimulating treatment has come into vogue again in thepractice of Dr. Todd and his followers. The compounds of mercuryhave yielded their place as drugs of all work, and specifics for thatvery frequent subjective complaint, nescio quid faciam,--to compoundsof iodine. [Sir Astley Cooper has the boldness,--or honesty,--tospeak of medicines which "are given as much to assist the medical manas his patient." Lectures (London, 1832), p. 14.] Opium is believedin, and quinine, and "rum," using that expressive monosyllable tomean all alcoholic cordials. If Moliere were writing now, instead ofsaignare, purgare, and the other, he would be more like to say,Stimulare, opium dare et potassio-iodizare.

I have been in relation successively with the English and Americanevacuant and alterative practice, in which calomel and antimonyfigured so largely that, as you may see in Dr. Jackson's last"Letter," Dr. Holyoke, a good representative of sterling old-fashioned medical art, counted them with opium and Peruvian bark ashis chief remedies; with the moderately expectant practice of Louis;the blood-letting "coup sur coup" of Bouillaud; the contra-stimulantmethod of Rasori and his followers; the anti-irritant system ofBroussais, with its leeching and gum-water; I have heard from our ownstudents of the simple opium practice of the renowned German teacher,Oppolzer; and now I find the medical community brought round by therevolving cycle of opinion to that same old plan of treatment whichJohn Brown taught in Edinburgh in the last quarter of the lastcentury, and Miner and Tully fiercely advocated among ourselves inthe early years of the present. The worthy physicians lastmentioned, and their antagonist Dr. Gallup, used stronger languagethan we of these degenerate days permit ourselves. "The lancet is aweapon which annually slays more than the sword," says Dr. Tully."It is probable that, for forty years past, opium and itspreparations have done seven times the injury they have renderedbenefit, on the great scale of the world," says Dr. Gallup.

What is the meaning of these perpetual changes and conflicts ofmedical opinion and practice, from an early antiquity to our owntime? Simply this: all "methods" of treatment end in disappointmentof those extravagant expectations which men are wont to entertain ofmedical art. The bills of mortality are more obviously affected bydrainage, than by this or that method of practice. The insurancecompanies do not commonly charge a different percentage on the livesof the patients of this or that physician. In the course of ageneration, more or less, physicians themselves are liable to gettired of a practice which has so little effect upon the averagemovement of vital decomposition. Then they are ready for a change,even if it were back again to a method which has already been tried,and found wanting.

Our practitioners, or many of them, have got back to the ways of oldDr. Samuel Danforth, who, as it is well known, had strong objectionsto the use of the lancet. By and by a new reputation will be made by